31 Cygni

31 Cygni (Cyg)

Several star systems (31 and 32 Cygni, Zeta Aurigae, 22 Vul, and VV Cephei) make up what is called the Zeta Aurigae type system. These star systems are unique because they allow study of the primary star's atmosphere. When the smaller blue star passes behind the primary star, the ingress and egress of the eclipse are times when the blue star's light is passing through the primary star's atmosphere. It is these parts of the eclipse that are of most interest as they yield information about the primary star's atmosphere.

31 Cygni is a 4th magnitude star and is easy to observe. It has a period of 10.4 years. As with the other stars of the zeta Aurigae group, the eclipse of 31 Cygni is shallow (0.12 magnitudes) in the "V" band but very pronounced (0.5 and 1.7 magnitudes respectively) in the "B" and "U" bands.

Reference: Stencel, R.E., Hopkins, J.L., Hagen, W., Fried, R., Schmidtke, P.C., Kondo, Y., Chapman, R.D., 1984, The Astrophysical Journal; THE 1982 ECLIPSE OF 31 CYGNI, 281:751-759, June 15.

31 CYGNI DATA

31 Cygni
V695 Cyg
HR7735
HD192577
SAO 49337
Name: Omicron1 Cygni

R.A. (2000) 20h 13m 37.8s
DEC. (2000) +46d 44' 29"

Distance: ? light years (160 pc)

Epoch: JD 2,437,685.65
Period: 3784.3 days (10.4 years)

Secondary Eclipse at Phase: 0.64 (2,421.95 days)

Ingress/Egress: 1.7 days
Totality: 61.2 days

Next Eclipse:
JD= 2,456,607.15 = Sunday, 10 November 2013

Secondary Eclipse:
JD= 2,459,029.10 = Sunday 28 June 2020

Maximum Separation Date - ?

Comparison Star:
30 Cygni * HR7730 * HD192514 * SAO 49332
R.A. (2000) 20h 13m 17.9s
DEC. (2000) +46d 48' 57"
I= 4.59 R= 4.64
V= 4.83 B= 4.92 U= 5.07

Check Star:
26 Cygni * SAO 49098 * HR7660 * HD190147
R.A. (2000) 20h 01m 21.5s
DEC. (2000) +50d 06' 17"
R - I= + 0.55
V= 5.05 B= 6.16 U= 7.18